Phase formation for the multi-component alloys has been predicted by calculating parameter Ω and δ for typical multi-component alloys reported. Here, Ω is defined as a parameter of the entropy of mixing timing the average melting temperature of the elements over the enthalpy of mixing, δ is the mean square deviation of the atomic size of elements. It shows that the high-entropy (HE) stabilized solid-solution is located at Ω ≥ 1.1 and δ ≤ 6.6%.